Isolation of a novel class of bZIP transcription factors that interact with ABA‐responsive and embryo‐specification elements in the Dc3 promoter using a modified yeast one‐hybrid system

摘要: Dc3 is a carrot lea class gene that abundantly expressed during somatic and zygotic embryogenesis. Its expression normally embryo-specific also can be induced by abscisic acid. The regulatory elements mediating the of reside within proximal promoter region (-117 to +26), which essential for ABA-induced expression. In this study, an optimized version yeast one-hybrid system has been used clone factors bind gene. Twenty-five million transformants were screened in single experiment, nine independent cDNA clones isolated from sunflower library encode proteins specifically functional cis-regulatory promoter. Analysis these showed they are derived three different mRNA species two basic leucine zipper proteins. regions proteins, named DPBF-1 2 (Dc3 Promoter-Binding Factor-1 2), respectively, nearly identical each other similar plant G-box binding factor GBF-4. Outside region, however, diverge significantly known factors. Both have transcriptional activity yeast, DNA as dimers. Unlike bZIP factors, recognize sequences containing ACACNNG core. Cloning demonstrates power approach when optimally applied.